First, description will be made on the format of a read-only memory (ROM) of a blue ray disc (hereinafter called a BD) used as a large capacity information recording medium using a blue laser.
The ROM format of BD is hierarchical and the uppermost layer is divided into a physical cluster part and a linking part. Of these, the physical cluster part is constituted of 16 address units, and each address unit is constituted of 31 data frames.
The data frame is constituted of user data record areas each called an ECC cluster and address data or user control data record areas each called a BIS cluster. Of BIS clusters, the address data record area is contained in the first three data frames of each address unit, and the BIS clusters in the remaining data frames are used as the user control data areas.
Each data frame is constituted of one data block 221 of top twenty bits and blocks obtained by dividing remaining data in the unit of 45 bits, 28 blocks in total. A DC control bit is added to the end of each block. This bit is controlled so that an absolute value of DSV corresponding to an occurrence rate of bits after modulation becomes near 0.
A bit train obtained in the manner described above is modulated by using a 1-7 modulation table and converted into a 1-7 pp modulation bit train, after the frame sync signal is prepared in accordance with a frame number or the like. The bit train modulated by using the 1-7 modulation table is a bit train of NRZI which inverts positive/negative pulses by 0 or 1. Therefore, actually recorded in a medium is a signal obtained by converting the NRZI signal through NZRI-NRZ conversion in such a manner that 0 and 1 are in one-to-one correspondence with the pit or land.
Recorded in the linking part are a top frame sync signal not contained in the physical cluster part and data of two frames having the frame structure similar to that of the physical cluster part.
It becomes necessary for optical discs of this type to additionally record identification information different for each of mass production reproduction only media, for example, to manage copyright and the like.
A method of realizing this is known. For example, a reflection film for reflecting read light is melted by irradiating a high output optical beam to a land area on a track of an information recording medium, to thereby lower a reflectivity and form a pseudo pit.
For example, International Patent Publication No. WO03/038822 proposes a method of changing some bits in a predetermined block by a high output beam and fixing the remaining bits, respectively in an information recording medium recorded with data modulated in a block unit.
However, according to the conventional techniques, when a pseudo pit is recorded in some record area, the record area is required to have always a land. Therefore, it is necessary to properly form a record area having a land when an information recording medium is manufactured, resulting in a complicated manufacture process.
The present invention has been made in consideration of the above issues, and an object of the present invention is to provide an information recording medium capable of being manufactured easily in the form of securely forming a land in an identification information record area and reliably recording identification information, a mastering apparatus for manufacturing the information recording medium, an identification information recording apparatus, an identification information reproduction apparatus and methods therefor.